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TITLE: CARCINOMA OF A THYROGLOSSAL DUCT CYST
SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds
DATE: July 3, 1991
RESIDENT PHYSICIAN: Lane Smith, M.D.,
FACULTY: Karen Calhoun, M.D.
DATABASE ADMINISTRATOR: Melinda McCracken, M.S.
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"This material was prepared by resident physicians in partial fulfillment
of educational requirements established for the Postgraduate Training
Program of the UTMB Department of Otolaryngology/Head and Neck Surgery
and was not intended for clinical use in its present form. It was
prepared for the purpose of stimulating group discussion in a conference
setting. No warranties, either express or implied, are made with respect
to its accuracy, completeness, or timeliness. The material does not
necessarily reflect the current or past opinions of members of the UTMB
faculty and should not be used for purposes of diagnosis or treatment
without consulting appropriate literature sources and informed professional
opinion."
ABSTRACT:
Thyroglossal Duct (TGD) Cysts are a common developmental abnormality.
Primary carcinoma can arise in these cysts, but it is a rare occurrence
with less then 150 cases reported in the literature. We present a case of
an 18 year old female with a papillary carcinoma of her TGD Cyst and a
benign thyroid nodule who underwent a Sistrunk excision of her TGD cyst
and a hemithyroidectomy. Histopathology of the TGD carcinoma is similar
to papillary carcinoma of the thyroid. The literature is reviewed.
Treatment of TGD carcinoma includes complete excision of the TGD cyst
using a sistrunk procedure. The thyroid is removed if there are
suspicious nodules or if the patient has a history of radiation to the
neck. Neck dissection is reserved for patients with positive nodes.
Patients are placed on suppressive doses of thyroid hormone and long term
follow-up is needed.
INTRODUCTION
Thyroglossal duct (TGD) cysts are twice as common as branchial cleft
abnormalities. After lymphadenopathy, they are the second most common
neck mass found in children. They are thought to be a persistence of the
tract through which the thyroid descends from the base of tongue on the
way to its final position in the neck. The persistent tract may then
dilate to form a cyst. Often a small amount of thyroid tissue is
implanted in the cyst wall. Rarely carcinoma can arise in a TGD cyst.
Less then 150 cases of TGD carcinoma have been reported in the literature.
We report a case of papillary carcinoma arising in a TGD cyst in a young
female who also had a concomitant thyroid nodule.
CASE REPORT
An 18 year old white female was referred to our clinic for a small
right lower lobe thyroid nodule. The patient had no complaints other then
occasional fatigue. On physical examination a 1 1/2 by 2 cm right firm
thyroid nodule was present as well as a 2 by 2 cm midline neck mass which
moved with deglutition. No other masses were found and the base of
tongue, as well as the rest of the physical exam was unremarkable.
Thyroid function tests were normal. A thyroid ultrasound showed a mixed
cystic and solid mass of the right lower lobe of the thyroid. A
pertechnetate and I-131 thyroid scan showed a hyperfunctioning "hot"
nodule in the right thyroid lobe. No mention was made of any thyroid
tissue located in the TGD cyst or in any other locations. A fine needle
aspiration (FNA) of the thyroid mass suggested that it was benign. The
FNA of the TGD cyst showed a cystic lesion with many psammoma bodies and
few atypical epithelial clusters. Because the finding of psammoma bodies,
the FNA was repeated on both the thyroid mass and the TGD cyst with the
same results. The patient was taken to the operating room where the TGD
cyst was removed using the sistrunk procedure. The patient also underwent
a right thyroid lobectomy and isthmusectomy. The left thyroid lobe was
palpated at the time of the procedure and found to be free of any nodules.
The postoperative course was unremarkable. The patient was placed on
levothyroxine 0.125mg every day. She has been followed for 12 months with
no problems or evidence of recurrence.
HISTOPATHOLOGY
Microscopic examination of the thyroid showed a benign thyroid adenoma
and otherwise normal thyroid tissue (fig. 1.) The thyroid ducts are
filled with colloid and these are surrounded by uniform cuboidal cells.
The adenoma shows a fibrous capsule with benign appearing cells with
slightly more open and larger nuclei. The cells are also more irregular
and the ducts smaller. The TGD cyst showed a fibrous cyst wall lined by
squamous epithelium (although they can be lined by respiratory
epithelium), and normal areas of thyroid nests located in the cyst wall
(figs. 2 and 3.) An area of papillary projections with fibromuscular
stroma covered by a single or bilayer of cuboidal cells is seen in the
cyst wall and lumen (fig. 4.) On higher magnification the cells are seen
to be irregular and vesicular filled with large open clear irregular and
piled-up nuclei (fig. 5.) Psammoma bodies, which are abnormal areas of
calcification, are seen as round lamellar areas which are stained purple
(fig. 6.) Psammoma bodies and the papillary projections are highly
characteristic of papillary carcinoma (figs. 4 and 6.) The carcinoma did
not extend beyond the cyst wall.
DISCUSSION
Less then 150 cases of carcinoma of the Thyroglossal Duct
have been reported. In the past it was thought to be secondary
to metastasis from the thyroid gland or from cancer in a pyramidal
lobe of the thyroid. It is now generally accepted that TGD
carcinoma arises from thyroid tissue remnants located in the cyst
itself. While TGD cysts occur most commonly in patients younger then age
20, TGD carcinoma occurs more commonly in older patients with an average
age close to 40. It appears to be slightly more common in females. The
female to male ratio was 3:2 in 115 cases reported in one review (10),
80% of the cysts were 2-5cm in size. The most common finding is an
asymptomatic mass. Other signs and symptoms include a rapidly enlarging
mass; a firm, hard or fixed midline mass, dysphagia, dysphonia, or a
recent change in the size of the mass, and the presence of
lymphadenopathy. A history of irradiation to the neck or mediastinum
should arouse suspicion of the possibility of carcinoma. However; most
commonly TGD carcinoma is not suspected at the time of surgery. To our
knowledge, this is the first reported case in which TGD carcinoma was
suspected from the FNA results. Psammoma bodies found in our patient are
a prominent feature of papillary carcinoma of the thyroid, and when this
is discovered, carcinoma is suspected. These findings were consistent
when the FNA was repeated. Papillary carcinoma is the most frequent
carcinoma found in a TGD cyst (80%). Other pathological types include
follicular or mixed papillary follicular carcinoma (9%), squamous cell
carcinoma (5%), adenocarcinoma (2%), anaplastic carcinoma (1%) and other
(3%). Metastasis to regional lymph nodes is fairly rare, occurring about
10% of the time. Originally, preferred treatment was wide excision of the
TGD cyst and hyoid bone, and a total or near total thyroidectomy. Reasons
for this included the multicentric nature of papillary carcinoma and the
now disproved theory that TGD carcinoma was due to a metastasis form the
thyroid gland. In a frequently quoted study (1), of 35 thyroids removed
because of carcinoma in a TCD cyst, only 4 (11%) contained malignant foci.
TGD carcinoma is now treated similarly to papillary carcinoma of the
thyroid. If the cancer has not invaded beyond the cyst wall, simple
complete excision of the cyst using the Sistrunk procedure is adequate.
If the carcinoma has extended beyond the cyst wall, wider excision of the
surrounding tissue is necessary. Thyroidectomy is recommended only if
there a thyroid mass or history of radiation to the neck. As with
papillary carcinoma of the thyroid, a modified neck dissection is
recommended only in the presence of suspicious or positive nodes.
Suppressive therapy is recommended for TGD carcinoma. All patients,
whether they receive thyroidectomy or not, should receive adequate doses
of thyroid hormone to suppress secretion of TSH. Papillary carcinoma is
a slow growing cancer with an indolent course. If the cancer is
completely excised, recurrence is rare. The majority of patients with TGD
carcinoma have had no recurrences and prognosis is good. However because
of the slow growth rate, long term follow-up is recommended. CONCLUSION
TGD carcinoma is a relatively rare cancer which arises form thyroid tissue
located in the duct itself. Most patients present with an asymptomatic
mass. Fine needle aspiration can be useful and may lead to the early
suspicion of TGD carcinoma. Treatment consists of complete excision of
the TGD cyst and cancer using the Sistrunk procedure. Thyroidectomy is
reserved for thyroid involvement or if the patient has a history of
radiation to the neck. Neck dissection is performed for those patients
with positive nodes, and all patients are placed on suppressive doses of
thyroid hormone. Long term follow-up is needed and the prognosis is very
good.
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BIBLIOGRAPHY
1. Bhagavan BS, Rao DRG, Weinberg T: Carcinoma of thyroglossal duct cyst:
case reports and review of the literature. Surgery 1970;67:281-292.
2. Fernandez JF, Ordonez NG, Schultz PN, Naguib AS, Hickey RC:
Thyroglossal duct carcinoma. Surgery 1991;928-935.
3.Grant CS, Hay ID, Gough IR, Bergstralh EJ, Goellner JR, McConahey WM:
Local recurrence in a papillary thyroid carcinoma: Is extent of surgical
resection important? Surgery 1988;954-960.
4. Judd ES. Thyroglossal-duct cysts and sinuses. Surg Clin North Am
1963;43:1023-32.
5. McNicoll MP, Hawkins DB, England K, Penny R, Maceri DR: Papillary
carcinoma arising in a thyroglossal duct cyst. Otolaryngol Head Neck Surg
1988;99:50-54.
6. Nussbaum M, Buchwald RP, Ribner A, Mori K, Litwig J: Anaplastic
carcinoma arising from median ectopic thyroid (thyroglossal duct remnant).
Cancer 1981;48:2724-28.
7. Page CP, Kemmerer WT, Haff RC, Mazzaferri EL: Thyroid carcinomas
arising in thyroglossal ducts. Ann Surg 1974;180:799- 803.
8. Roses DF, Snively SL, Phelps RG, Cohen N, Blum M: Carcinoma of the
thyroglossal duct. Am J Surg 1983;145:266-269.
F9. Topf P, Fried MP, Strome M: Vagaries of thyroglossal duct cysts.
Laryngoscope 1988;98:740-742.
10. Wiess SD, Orlich CC: Primary papillary carcinoma of a thyroglossal
duct cyst: report of a case and literature review. Br J Surg
1991;78:87-89.
F11. Zimmerman D, Hay ID, Gough IR, Goellner JR, Ryan JJ, Grant CS,
McConahey WM: Papillary thyroid carcinoma in children and adults:
long-term follow-up of 1039 patients conservatively treated at one
institution during three decades. Surgery 1988;104:1157-66.
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1. Histopathology of the thyroglossal duct cyst (TGDC) carcinoma is
similar to
a. medullary carcinoma of the thyroid
b. papillary carcinoma of the thyroid
c. squamous cell carcinoma of the aerodigestive tract
d. follicular carcinoma of the thyroid
2. In the patient with TGDC carcinoma without a history of radiation
therapy to the neck and without cervical metastases, treatment
consists of
a. complete excision of the TGDC using the Sistrunk procedure
with suppressive doses of thyroid hormone and longterm followup
b. cervical lymphnode dissection
c. total thyroidectomy
d. radiation therapy
3. In relation to other masses in the neck, TGDC are
a. half as common as branchial cleft abnormalities
b. the most common neck mass found in children
c. frequently found in association with carcinoma of the thyroid
d. rarely found to contain carcinomatous elements
4. Thyroglossal duct cysts are thought to arise as a result of
a. midline endodermal fusion faults
b. metastasis from a carcinoma of the thyroid gland
c. a persistence of the tract through which the thyroid descends from
the base of the tongue
d. hamartomas
5. Which of the following is highly characteristic of papillary carcinoma
of the thyroid?
a. psammoma bodies and papillary projections
b. single layer cuboidal epithelium
c. rests of normal thyroid tissue
d. squamous or respiratory epithelium lining the cyst
6. Preferred treatment consists in
a. wide excision of the TGDC and hyoid bone, and total or near-total
excision of the thyroid gland
b. simple excision of the cyst
c. suppressive treatment with thyroid hormone
d. a management plan based on the presence or absence of cyst wall
invasion, prior radiation treatment to the neck, and presence
absence of cervical lymphnode metastases
7. Suppressive thyroid hormone therapy is recommended for
a. cysts containing rests of thyroid tissue
b. symptomatic TGD cysts only
c. all patients with TGDC carcinoma, to suppress TSH
d. patients with cervical lymphnode metastases
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